1. Field of the Invention
This invention relates to machines for separating mixed fluids. More particularly this invention relates to a rotating centrifuge-type machine which may be used, for example, to separate oil and water.
2. State of the Art
A fluid or mixture composed of two or more immiscible components, typically liquids of differing densities will, in the presence of the earth's gravitational field, will typically separate into layers with the least dense floating on top of the next most dense. With one component separated from the other, an interface or boundary between the two components is formed. The interface or boundary is typically quite distinct.
The process of gravitational separation may take a significant period of time based on, among other things, the volume of the involved fluids, the densities of the fluids, viscosity, temperature, and the like. To avoid delay and to expedite the separation process, it has long been recognized that the gravitational separation process may be greatly enhanced with regard to time and separation quality by replacing earth's "gravitational acceleration" with centrifugal force. That is, the fluids to be separated are placed in a container or vessel which is then spun to impose centrifugal forces. Based on, for example, the rotation rate, the force field thus provided may have a magnitude amounting to hundreds or even thousands of "g's." The gravitational force at sea level is sometimes regarded as 1 "g" and is typically presented as an acceleration of 32 feet per second per second. Simply stated, the force to separate the liquids may be up to several hundreds or thousands of times stronger than the earth's gravitational force.
Centrifuges or separators to effect the separation of two liquids using centrifugal force are well known. U.S. Pat. No. 4,525,155 (Nilsson) discloses a typical centrifuge of the type for separating two liquids. However, the Nilsson machine appears to have a limited capacity or flow rate due to its relatively small weir structures. Some centrifuges need a complex and expensive construction in order to obtain satisfactory separation efficiency. U.S. Pat. No. 5,387,342 (Rogers, et al.) and U.S. Pat. No. 5,582,724 (Rogers, et al.), as well as U.S. Pat. No. 4,525,155 (Nilsson) are illustrative of such machines.
Centrifuges are not typically recognized to be suitable or adaptable to deal with different input fluids. That is, the mixture may change and be made up of different pairs or combinations of fluids of varying compositions, component densities, and flow rates. External control systems or requirements for frequent adjustment to obtain satisfactory operation are typically needed for those machines having provisions to adapt to varying or differing mixtures or conditions of operation. Besides having only limited effectiveness, such designs are generally complicated to build and operate, making them inefficient or uneconomical.
Some known centrifuges or separators are incapable of operation where input flow and output flows must be maintained at certain pressures. For example, the centrifuges disclosed by U.S. Pat. No. 5,582,724 (Rogers, et al.) have no ability to deliver separated fluids into pressurized lines. Centrifuges of the type illustrated by U.S. Pat. No. 4,525,155 (Nilsson) utilize a paring disk discharge which limits output pressures.
Known centrifuges are not effective if the fluid mixture to be separated contains gas and solid components as well as liquids. That is, centrifuges that are effective in separating two liquids of different densities have no ability for separating and discharging substantial proportions of gas entrained in the input flow. U.S. Pat. No. 5,582,724 (Rogers, et al.) does not provide a means to extract gas from the mixture or from the separated or separating fluids. Further, there is no provision for discharging solids such as sludge, grime, entrained dirt and stone and other physical impurities which tend to build up in the interior of the centrifuge, resulting in a need for periodic cleaning. The centrifuge or U.S. Pat. No. 4,525,155 (Nilsson) does have structure for discharging solids, but the mechanism provided to do so adds greatly to the cost and complexity of the machine.
From the foregoing, it will be appreciated that it would be an advancement in the art to provide a centrifuge of uncomplicated and inexpensive construction, which would automatically separate fluids of varying composition and flow rates and having a wide range of component densities without requiring external control or adjustment of the centrifuge.
It would be a further advancement in the art to provide such a centrifuge that is capable of higher flow capacity for its size than centrifuges in the art. It would also be an advancement in the art to provide a capability to separate fluids at various conditions of fluid pressure, and in the presence of gas and solid components, while also achieving the other advancements mentioned.